What’s Growing on my Rocks?

[Sailor]

I have a 100 gallon reef tank that’s been running for about 18 months and it seems like I’m gong through the ugly stage all over again. There’s some nasty stuff growing on my sand bed and something totally different growing on some of the rocks. I’ll deal with each of these separately once I identify the specific pest(s).

Right now I was hoping someone could tell me what is that rust-colored fuzzy stuff growing on my rocks. Here are two photos of the same rock, one under white light and the other under the regular (blue) aquarium lights. While the stuff growing on the sand bed responds to the light cycle — it turns dark brown by the afternoon and virtually disappears at night — the fuzzy stuff on the rocks does not. It keeps its color and shape. What is it?

 

[thatmanMIKEson]

looks like cyano, does it blow off the rock easily?

 

[Salty_Northerner]

Does it blow off easy using a turkey baster by chance?

 

[Salty_Northerner]

looks like cyano, does it blow off the rock easily?

Only cyano I've ever seen is reddish purple.. this is brown. Is there brown cyano, I'm asking because I only know of the red/purple stuff.

 

[thatmanMIKEson]

Only cyano I've ever seen is reddish purple.. this is brown. Is there brown cyano, I'm asking because I only know of the red/purple stuff.

yup there's brown purple greenish yellow it also depends on the lighting every color you see is actually reflected light and taken with a camera so the actual color may differ from "brown" but a good question is if it blows of the rock easily , that will help to narrow it down.

 

[EeyoreIsMySpiritAnimal]

yup there's brown purple greenish yellow it also depends on the lighting every color you see is actually reflected light and taken with a camera so the actual color may differ from "brown" but a good question is if it blows of the rock easily , that will help to narrow it down.

If it doesn't blow off easily it could still be cyano... I had some that was like rubber and was easily removed with tweezers, but stayed put when I used a turkey baster...

 

[thatmanMIKEson]

If it doesn't blow off easily it could still be cyano... I had some that was like rubber and was easily removed with tweezers, but stayed put when I used a turkey baster...

thats true, but if it does, that's a quick indication of what it could possibly be.

 

[Salty_Northerner]

yup there's brown purple greenish yellow it also depends on the lighting every color you see is actually reflected light and taken with a camera so the actual color may differ from "brown" but a good question is if it blows of the rock easily , that will help to narrow it down.

Thanks, I didn't know that. My test tank is only 4 months old and I knew I'd see an ugly stage and I chanced it hard! Like an old kind of hard. I had some brown stuff growing my life Rock and after about 4 weeks that's when it appeared. I turkey basted it off and never seen it again. And to this day I have no idea what it is or was.

 

[Sailor]

I tried blowing this rust-colored stuff off the rocks with a turkey baster a few days ago and some of it did come off, but not very easily. I suspected this might be cyano so I’ve been running Chemi-Clean for two days now. I used Chemi-Clean once before (about a year ago) when I had a redish slime on the sand, and it worked well. This time I saw no change at all in two days — until I tried the turkey baster again this morning. Now the stuff comes off the rocks easily. I imagine the Chemi-Clean weakened it. Now I’ll have to wait and see if it comes back.

Meanwhile, I still have to deal with the brown stuff in the sand bed. Over the last two weeks I’ve been vacuuming the brown right out of the sand every couple days, but it comes right back in a day or two. I’m not just sucking the detritus out of the sand, I’m actually pulling the brown sand out and sanitizing it so I can put back in the tank once I get this under control.

I don’t know if the brown stuff in the sand is diatoms or dinoflagellates so I’m not sure how to treat the problem. Perhaps this image can help identify the pest. This is what a drop of water taken from the bucket of brown sand looks like under a microscope. This is actually a still taken from a video (which I wish you could see but I seem to be having some sort of compatibility issue uploading videos). Every one of those tiny dots in that image is an individual organism swimming around in that drop of water and it appears that they somehow eventually join together in clusters or strands. Any idea what this is?